This invention relates to the processing of granular starch for use as a carrier for absorbed functional substances. More particularly, this invention provides a microporous granular starch matrix material useful for absorption and releasable containment of any of a wide variety of useful compositions. Absorbed compositions are released from the porous granular starch matrices by diffusion into surrounding fluids, by mechanical compression, or by chemical degradation of the starch matrix.
It has been known for quite a number of years that digestion of starch in food begins in the mouth on contact with salivary alpha-amylase. Starch digestion is completed in the duodenum of the small intestine where the starch granules come into contact with pancreatic alpha-amylyase and intestinal beta-amylase. Starch granules taken from the duodenum or natural starch granules that have been treated with alpha-amylase or glucoamylase in vitro for a period of time are noted under microscopic examination to have numerous holes or pores ranging over the entire surface. The number, size and depth of the pores depend upon the extent of the enzyme action. As normal digestion continues in the gastrointestinal tract the granule is entirely disintegrated by the alpha-amylase, by the normal beta-amylase of the intestine and by maltase which is also present.
In accordance with the present invention microporous starch granules are used as a carrier for a wide variety of functional substances. The granules are partially hydrolyzed with alpha-amylase and/or glucoamylase and optionally treated chemically to modify structural integrity and surface characteristics. The amylase-treated granules have numerous pores leading from the granule surface to the granule interior giving the treated granules a sponge-like appearance on microscopic examination. Substances can be readily absorbed into the porous granular starch matrix. That property also allows the present porous granular starches to find use as adjuvants for antiperspirants and as bulking agents for foods and drinks.
Use of granular starch matrices in accordance with the present invention allows for the preparation of new forms of art-recognized compounds and compositions having utility in the areas of food/nutrition, topical creams and lotions, cosmetics, agricultural products, and products for human and veterinary medicine. Such novel formulations can be designed to enhance or prolong the functional characteristics of absorbed compositions. For example, substances naturally of a liquid character can be formulated into a powder, paste or cream formulation, more easily adapted for packaging or for practical utility, such as for sustained release of said compositions.